Electrical indicator.



9 9 m m .L e a in e t n e t a P D N A R G E L c at L L E D D A w M a 8 A 3 0 ELECTRCAL INDICATOR.

(Applimtion filed Feb. 18, 1899) 2 Sheets-Shoat l,

(No Model.)

mvmoa WITNESSES:

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m. 634,488. Patented Oct; 10, I899.

' M. WADDELL & C. LEGBAND.

ELECTRICAL INDICATOR.

(Application. min. 18, 1599. (No Model.) 7 2 Sheets-Sheet 2.

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nonreonnnr WADDELL, on NEW roan, N. Y.,' AND CHARLES LEGRAND, or WESTFIELD, NEW JERSEY; sun) LEGRAND ASSIGNOR TO SAID IVADDELL.

ELECTRICAL lNDiCATO R.

SPECIFICATION forming part of Letters Patent No. 634,488, dated October 10 1899. Application filed February 18, 1899." Serial K037053753. (No model.)

T 6055 107607 i may C W/ 6 M: other. B is abase-plate having an internal 'Be it known that we, MONTGOMERY WADL chamber divided into forward and rear DELL, a subject of the Queen of Great-Britain, parts by an air-flow resistance consisting of residingin the city of New York, State of New a capillary tube c. Air or other gas under 5 York, and CHARLES LEGRAND, a subject of pressure issupplied to the rear portion of the the King of Belgium, residing at Westfield, in chamber through the openings 1') by an airthe county of Union and State of New Jersey, pump or other suitable source, whence it have invented certain new and useful Imleads through the capillary tube into the forprovementsin Electrical Indicators, of which ward portion of the chamber and then to the 60. 10 the following is a full, clear, and exact desurface of the liquid-column in A. The scription. means for inserting the capillary tube is a This invention relates to eiectricalindicafeature of the present invention. In the tors or instruments whose function is to show former application referred to the tube was i at any time the condition of the current fiowwound around the outside of a plug, whereas I5 ing in an electric circuit or circuits. in the present case the tube is coiled inside The invention consists of certain improveof a hollow plug a, one end of which is solid ments over the invention -of Montgomery and tapered to make a tight fit with the walls \Vaddell, described in his application filed of the'air-charnber. One object in using a January 10, 1899, Serial No. 701,597. In that hollow plug is to be able to use various other 20 application is described an instrument wherekinds of air-flow resistance, as well as the in the condition of the current flowing in a capillary tube, the preferred resistance being circuit is indicated by the height of a column easily contained in the chamber of the plug. of liquid, such height being raised or lowered To control the pressure in the forward porby the pressure of air or gas, which in turn tion of the air-chamber, which, as before 25 is controlled by the current beingindicated. stated, acts upon the surface of the column The principle of operation described in said of liquid, a plug (1, with a passage d leading application is used in the instrument defrom the chamber to the atmosphere, is used. scribed in the present case; but the improve- This plug is shown in detail in Fig. 2, Wherement herein consists in counterbalancing the in it will be seen that the single passage d is 0 valve controlling the pressure of air, whereby covered at the top by a very small and light it will require less current to operate the indisk valve 0?, which is held in place by a strument, and the instrument is easier to adsleeve (i having lateral openings d through just. In the present instrument the mercurywhich'the air or gas which is allowed to escontacts described in the previous applicacape from the passage has an exit. The un- 35 tion are dispensed with and a novel construcder surface of the valve makes a smooth even tiou substituted for them. The details of fit with the top ofthe plug, which at that construction also form a part of the present point is merely a flange surrounding the esiuvention. cape-passage.

In the accompanying drawings, Figure 1 is Mounted abovethebase-plate B is a per- 40 a central vertical section of the improved inmanent .magnet ill, of horseshoe form, the strument, parts being shown in elevation. legs being partially connected by an iron Fig. 2 is an enlarged detail of the valve. Fig. plate m, having 'a circular vertical opening 3 is a plan of the spool and its balancing-supm in one end, through which a leg. of the port. Fig. 4 is arear view of the magnet and magnet passes. The end of the leg is made 5 45 counterbalancing devices. Fig. 5 is a seccylindricalandofless diameter thantheopention on line a: a: of Fig. 3. 7 ing in, so as to leave an annular spaceform- Referring first to Fig; l for a general uning a field of force. The magnet is support derstanding oft-he instrument, A represents ed above the plate by means of two brass theindicating-column, communicating at the blocks 0, upon which is placed a plate of hard mo 5 lowerend withastand-pipe A, the liquid conrubber or other insulating material 0', to tained therein flowing freely from one to thev which the cross-piece of the magnet is secured, the rubber plate being also rigidly secured to the blocks 0. This arrangement insulates the magnet from the blocks. The latter carry metallic studs 0 which pass downward through the baseplate and are fitted with suitable binding devices for the electrical conductors, through which the current flows to actuate the instrument. The blocks 0 and the studs. 0 are insulated from the base-plate in the manner shown. In'the space immediately beneath the magnet and between the blocks we arrange a balancingarm 1), screw-threaded at its rear end to re ceive threaded weights 1) in the form of nuts and at its forward end carrying a spool or frame q, of hard rubber or other material, the upper diameter of which receives a coil of wire q. ,The arm 1) rests on the valve-disk and determines by its pressure thereon the pressure in the forward chamben The balancingarm carries a cross-barp of hard rubher or other insulating material, which is firmly secured thereto by nuts p. At each extremity of the cross-ha r is provided a clamp consistingof a metallic platep, held against the side of the cross-bar by screws 11 In each of these clamps is fixed a very thin strap or ribbonp", of metal, projecting upward and passing into clamps 0 on the blocks 0, similar in construction to those on the cross-bar. These straps of metal support the balancingarm and the devices which it carries, forming a pivot on which the arm may turn through its very slight working angle without substantial resistance or friction. The terminals of the coil 1 lead, respectively, to the clamping-plates p and the steel straps serve to connect said clamps with the brass blocks 0, thus establishing a complete circuit between the binding-posts of the instrument through the coil q. To prevent derangement of'the balancing-arm thus delicately mounted, we embrace its forward portion in a pair of blocks .9, in which it has sufficient play to per form its functions, but being so confined as to prevent displacement. These blocks are secured to the under side of the magnet.

The spool q projects into the annular field of force of the magnet sufficiently to bring the entire coil under the magnetic influence.

The operation of the instrument is substantially the same as that of the instrument described inthe former application; but in brief it may be stated that when the air-pressure is admitted to the chamber above the surface of the liquid-column the latter is forced downward to the zero-point of the scale, which is determined by the air-pressu re in the forward chamber and the opposing pressure upon the valve-disk. It will be observed that if for any reason the liquid-level does not coincide with the zero-mark on the scale adjacent to the column it may readily be made to do so by adjusting the position of the counterweights p, and thereby adding to or decreasing the pressure of the arm upon the valve, This is one of the advantages claimed.

current flowing.

\Vhen the zero-point is properly adjusted, the current of proper polarity m ay be allowed to flow through the coil Q, whereupon a tendency will be developed to lift the coil and spool,depending upon the strength of As the pressure on the upper side of the valve is thus relieved the airpressure on the under side that is necessary to balance it becomes less and an increased flow of air takes place. The level of the liquid-colun1n accordingly rises to a point corresponding to the strength of current flowing. A decrease in the current reverses these actions.

Since the weight of the spool and coil is offset to any degree desired by the counterweight, it is obvious that the instrument may be operated with very small expenditure of current, and it'is also evident that the valve will be more sensitive than the one described in the previous application, for that valve 'was held down by the entire weight of the coil and spool and it was necessary to provide a larger capacity of escape-port for a given air-pressure. Dispensing with the mercurycontacts is also an important advantage.

Having described our invention, we claim- 1. In an electrical indicator, the combination of a column of liquid whose level indicates the condition of thecurrent flowing, an air-supply acting upon the liquid to change its level, a valve controlling the pressure of the supply, a counterbalanced weight resting upon the valve and means whereby the pressure of the weight upon the valve is varied in accordance with variations in the current flowing, substantially as described.

. 2. In an electrical indicator, the combination of an indicating element, an air-supply actuating the same, and a counterbalanced valve controlling the pressure of the supply of air, said valve being operated by variations in the current flowing.

3. In an electrical indicator, the combination of an indicating element, an air-supply actuating the same, a valve controlling the pressure of the supplied air, a spool carrying a coil of wire through which the indicated current flows, a magnetic field of force in which said coil is located, a counterbalance for the weight of the spool and coil, the valve being controlled by said spool and coil, sub stantially as described.

4:. In an electrical indicator, the combination of means for creating a field of force, a

coil of wire and its spool located therein, a tilting arm by which said spool and coil are carried, a counterweight therefor, a valve upon which the arm bears, said valve controlling pressure of air, and an indicating element operated by the pressure, substantially as described.

5. In an electrical indicator, the combination of means for creating a field of force, a spool and coil located therein a tilting arm carrying at one end the spool and coil and at the other end a counterweight therefor, a pair of metallic straps suspending said arm and seal a fluid-chamber, the fluid-flow resistance being contained inside the plug'and communicating through both ends thereof with the fluid-chamber, substantially as described.

In Witness whereof We subscribe our signatures in presence of two witnesses.

MONTGOMERY WADDELL. CHARLES LEGRAND.

Witnesses:

FRANK S. OBER, GEO. S. KENNEDY. 

